/Engine/Source/Runtime/Core/Public/Containers/UnrealString.h
Construct from contiguous range of characters with extra slack on top of original string length
template<typename CharRangeType, typename [TEnableIf](API\Runtime\Core\Templates\TEnableIf)< [TIsCharRangeNotCArrayNotFString](API\Runtime\Core\Templates\TAnd)< CharRangeType >::Value >::Type *> FString ( CharRangeType && Str, int32 ExtraSlack )